Abstract:

Using tetrabutyl titanate, erbium oxide and nitric acid as raw materials, TiO₂: Er³⁺ hollow spheres were prepared with carbon spheres as template. The structures and morphologies of the obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The photocatalytic activities were studied by degradation of organic pollutants (rhodamine B, methylene blue, alizarin red, methyl orange) using UV-Vis spectrophotometer. The factors, such as Er³⁺ dopant concentration, pH of the dye solution, on the photocatalytic activities were discussed. The results showed that uniform and well crystallized TiO₂: Er³⁺ hollow spheres in an anatase phase, with diameter of 120 nm could be obtained via carbon-template method followed by a heat treatment at 600℃ for 3 h. The specific surface area of the TiO₂: Er³⁺ hollow spheres was about 60.5 m²/g. When the Er³⁺ dopant concentration was 0.5 mol% of Ti⁴⁺ ions in TiO₂, the photocatalytic activity of catalyst on the methyl orange was better than the other samples. Among the four different organic pollutants, the photocatalytic activity on the alizarin red was best. TiO₂: 0.5mol%Er³⁺ showed the better photocatalytic properties than the undoped TiO₂. The photodegradation efficiency of alizarin red with TiO₂: 0.5mol%Er³⁺ was 30% higher than that with the undoped TiO₂ under UV light irradiation.

Key words: Er3+ doping, TiO2, hollow spheres, photocatalytic degradation